SPECS: Steel, black, matte finish. Includes washer. FSC556 and CQB models fit AR-15/M16/M4 and clones chambered in .223/5.56mm, with ½”-28 tpi RH muzzle threads. FSC556 - 21⁄8" (5.4cm) long x 7⁄8" (2.2cm) diameter. 2.2 oz. (62g) wt. FSC556 YHM – 25⁄8” (6.7cm) long x 7⁄8” diameter. 4.9 oz. (138g) weight. FSC556 QDSS – 17⁄8” (4.8cm) long x 7⁄8” diameter. 2.3 oz. (64g) weight. FSC30 - Fits AR-style rifles in 6.8mm, .270, and .308/7.62. 2¾” (7cm) long x .960” (2.4cm) diameter. 3.6 oz. (101g) weight. 5⁄8"-24 tpi RH thread. Includes ½”-28 adapter. CQB – 2¾” (7cm) long x 13⁄8” (3.5cm) diameter. 9.1 oz. (258g) weight. ½”-28 tpi RH thread.